11.16 Pityriasis Rosea

Presentation

Patients with this benign disorder often seek acute medical
help because of the worrisome sudden spread of a rash that
began with one local skin lesion. This "herald patch" may
develop anywhere on the body and appears as a round 2-6 cm
mildly erythematous scaling plaque. There is no change for a
period of several days to two weeks; then the rash appears,
composed of small (l-2cm), pale, salmon-colored, oval
macules or plaques with a coarse surface surrounded by a rim
of fine scales. The distribution is truncal with the long
axis of the oval lesions running in the planes of cleavage
of the skin (parallel to the ribs). The condition may be
asymptomatic or accompanied by varying degrees of pruritis
and, occasionally mild malaise. The lesions will gradually
extend in size and may become confluent with one another.
The rash persists for 6-8 week then completely disappears.
Recurrences are uncommon.

What to do:

Reassure the patient about the benign nature of this
disease. Be sympathetic and let him know that you
understand how frightening it can seem.

Draw blood for serologic testing for syphilis (e.g.,
VDRL). Secondary syphilis can mimic pityriasis rosea. Make
a note to track down the results of the test.

Provide relief from pruritis by prescribing hydroxyzine
(Atarax) 50mg q6h or an emollient such as Lubriderm. Tepid
corn starch baths (1 cup in 1/2 tub of water) may also be
comforting.

Inform the patient that he should anticipate a 6-8 week
course of the disease, but to seek followup care if the
rash does not resolve within 12 weeks.

What not to do:

Do not use topical or systemic steroids. These are only
effective in the most severe inflammatory varieties of this
syndrome.

Do not send off a serologic test for syphilis without
assuring the results will be seen and acted upon.

Discussion

Pityriasis rosea is seen most commonly in adolescents and
young adults during the spring and fall seasons. It is
probably a viral syndrome. The "herald patch" may not be
seen in 20-30% of the cases and there are many variations
from the classic presentation described. Other diagnostic
considerations besides syphilis include tinea corporis,
seborrheic dermatitis, acute psoriasis, and tinea
versicolor.